The invention lies in the field of paper processing, and relates to a method and a device for separating continuously conveyed material webs, wherein the separation is effected roughly parallel to the conveyor direction. The method and the device are particularly suitable for separating multi-sided printed products which are designed as two-ups or multiple-ups, and which comprise two or more than two equal or different exemplars, and which are conveyed in a flow in a manner such that exemplars connected to one another in a printed product are arranged next to one another, and, for all printed products, are aligned to one another in the conveyor direction. Of course, other applications of the method and device according to the invention are also conceivable.
In contrast to the process of cutting printed products, in which edge regions are cut away from the printed products in a head cut, foot cut and/or front cut, and for this reason the quality of the paper edges is only important on the side of the printed product, but not on the side of the cut-away section, on separating multiple-ups, it is important that both edges arising due to the separation have an as high quality as possible.
It has been found that an edge quality which is equally good on both sides when separating continuously conveyed material webs may be better achieved if the separation is not effected by a single cut, but by way of creating a separating gap either by way of sawing or milling, and the removal of swarf-like waste, or by way of parallel cutting along two parallel cutting lines which run as closely as possible to one another, wherein a narrow waste strip arises between the two separated parts.
The publication CH-666651 describes a device for separating continuously conveyed material webs, in particular from an imbricate flow of printed products, with the help of a separating disk which is rotatably driven and which comprises two circular cutting edges arranged in each case in the plane of an end-face of the disk. Each of the two cutting edges thereby is arranged cooperating with a counter-knife rotating in the opposite direction, wherein the counter-knives too have a circular cutting edge in each case. The material webs are pressed against one another for the separation. The separating disk for example has a hollow grinding around its periphery, or consists of two disk parts applied against one another, wherein the sides of the two disk parts which face one another are obliquely ground on their periphery. Evidently, the material webs in such a device are separated by two cutting processes running in parallel, in a manner such that a waste strip arises between the two separated product parts.
It is also suggested, in the same publication, to design the separating disk as a milling disk or saw disk with a saw-tooth grinding, thus not as a cutting tool but as a material-removing tool. In the case of the saw-tooth grinding, it is suggested instead of the setting of the teeth common for sawing, to arrange these on two symmetrical disk parts which correspond to the disk parts mentioned further above.
A rotating separating disk for separating continuously conveyed material webs is likewise disclosed in the publication WO-2005/102624. This, on its periphery, comprises alternating saw teeth and peeling knives, wherein the cutting edges of the peeling knives lie in an alternating manner in the plane of the one, and in the plane of the other end-face of the separating disk. The function of the saw teeth lies in clearing a separating gap in a material-removing manner. The function of the peeling knife lies in improving the paper edges arising from the clearing, on both sides of the sawn gap, in a peeling cut. Thereby, the separating disk is operated in the opposite direction with regard to the conveying, in a manner such that the peeling knives cut essentially in the direction of the material webs and counter to the conveyor direction, by which means the application of a counter-knife is rendered superfluous for the peeling procedure (as well as, of course, for the sawing procedure).
It has been found that there is scope for improvement with regard to the edge quality, on separating continuously conveyed material webs. It is, therefore, the object of the invention to provide a further method and a further device, which are suitable for the separation of essentially continuously conveyed material webs, wherein the paper edges arising on separation should fulfill high demands with regard to the quality. Moreover, the method according to the invention should permit a device which is very space-saving.